What component of an on-site sewage system is exempt from watertight requirements?

The soil dispersal component of an on-site sewage system is exempt from watertight requirements because its primary function is to facilitate the natural treatment and dispersal of wastewater into the soil. Unlike enclosed components such as septic tanks, pump chambers, and holding tanks, which are designed to contain liquids and prevent leaks, the soil dispersal component operates on the principle of allowing liquid to percolate into the ground.

This exemption is based on the understanding that the soil itself acts as a natural filter, providing necessary treatment before the water re-enters the groundwater system. As a result, containment or watertightness is not a concern for soil dispersal components, whereas maintaining a watertight structure is critical for the other elements to prevent contamination of the surrounding area.